Track Shared Runners duration separate from CI minutes consumption

shared_runners_duration will always be tracked for a namespace
even though the CI minutes consumption is 0 because the project
is public or the namespace has unlimited CI minutes.

Changelog: added
EE: true

ee/app/services/ci/minutes/update_build_minutes_service.rb

@@ -6,33 +6,17 @@ module Ci
       # Calculates consumption and updates the project and namespace statistics(legacy)
       # or ProjectMonthlyUsage and NamespaceMonthlyUsage(not legacy) based on the passed build.
       def execute(build)
-        if Feature.enabled?(:ci_always_track_shared_runners_usage, build.project, default_enabled: :yaml)
-          return unless build.complete?
-          return unless build.duration&.positive?
-          return unless build.shared_runner_build?
-
-          ci_minutes_consumed = ::Gitlab::Ci::Minutes::BuildConsumption.new(build, build.duration).amount
-
-          update_usage(build, ci_minutes_consumed)
-        else
-          legacy_update_minutes(build)
-        end
-      end
-
-      private
-
-      def legacy_update_minutes(build)
-        return unless build.cost_factor_enabled?
         return unless build.complete?
         return unless build.duration&.positive?
+        return unless build.shared_runner_build?
 
-        consumption = ::Gitlab::Ci::Minutes::BuildConsumption.new(build, build.duration).amount
-
-        return unless consumption > 0
+        ci_minutes_consumed = ::Gitlab::Ci::Minutes::BuildConsumption.new(build, build.duration).amount
 
-        ::Ci::Minutes::UpdateProjectAndNamespaceUsageWorker.perform_async(consumption, project.id, namespace.id, build.id)
+        update_usage(build, ci_minutes_consumed)
       end
 
+      private
+
       def update_usage(build, ci_minutes_consumed)
         ::Ci::Minutes::UpdateProjectAndNamespaceUsageWorker
           .perform_async(ci_minutes_consumed, project.id, namespace.id, build.id, { duration: build.duration })

ee/config/feature_flags/development/ci_always_track_shared_runners_usage.yml

----
-name: ci_always_track_shared_runners_usage
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/72316
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/343258
-milestone: '14.4'
-type: development
-group: group::pipeline execution
-default_enabled: false

ee/spec/services/ci/minutes/update_build_minutes_service_spec.rb

@@ -128,14 +128,6 @@ RSpec.describe Ci::Minutes::UpdateBuildMinutesService do
 
           subject
         end
-
-        context 'when feature flag ci_always_track_shared_runners_usage is disabled' do
-          before do
-            stub_feature_flags(ci_always_track_shared_runners_usage: false)
-          end
-
-          it_behaves_like 'does nothing'
-        end
       end
 
       context 'when statistics and usage have existing amounts' do